Plasticized polypropylene thermoplastics

ABSTRACT

The invention is directed to a plasticized polypropylene thermoplastic composition comprising a blend of A) from 50 to 99.9 wt % of a thermoplastic polymer derived from polypropylene, optionally with one or more copolymerizable monomer selected from C 2 -C 10  α-olefin or diolefin, said polymer having a melt flow rate (MFR) (ASTM D1238) of from 0.5 to 1000 and a crystallinity by differential scanning calorimetry of from 0 to 70%; B) from 0.1 to 50 wt % of at least one ethylene copolymer having a weight-average molecular weight (M w ) (GPC) of from 500 to 10,000, a molecular weight distribution (MWD) (GPC) of from greater than 1.5 to less than or equal to 3.5, and a comonomer content of from greater than or equal to 20 mol % to less than 70 mol %; and optionally, C) from 0 to 20 wt % of a thermoplastic polypropylene modifier compound other than that of B).

FIELD OF INVENTION

[0001] This invention relates to hydrocarbon plasticizers forpolypropylene thermoplastics.

BACKGROUND

[0002] The blending of plasticizers in general with thermoplastics andthe resulting plasticization of those thermoplastics are well known andmany reviews have been written. A plasticizer is generally an organiccompound incorporated into a high polymer, such as for example athermoplastic, to desirably facilitate processing, increase itsworkability, flexibility, and/or distensibility of the polymer.

[0003] Within the last few years efforts have been made in the field ofplasticizers to better understand factors which governplasticizer/thermoplastic miscibility. Examples of a thermoplastic andplasticizer include polypropylene and low molecular weight polyolefins,respectively. Polypropylene is an inexpensive polyolefin engineeringthermoplastic that is generally stiff and even brittle below roomtemperature especially for highly stereoregular polypropylene.Tackifiers are examples of low molecular weight polyolefinsplasticizers. Examples of tackifiers include hydrocarbon resins derivedfrom fractionated petroleum distillates, coal tar, turpentine fractionsand from copolymerization of pure aromatic monomers. However, thesetackifiers typically have high glass transition temperature (T_(g)) andhigh solubility parameter. As such, upon blending, these tackifiers tendto raise the T_(g) of the polypropylene. Increasing the T_(g) increasesthe stiffness of polypropylene.

[0004] Other plasticizers, which have low T_(g), (below −20° C.) such asethylene-propylene rubber, ethylene-butene copolymer (having a M_(w)greater than or equal to 20,000), are immiscible with the polypropylene.Plasticizers which are immiscible with polypropylene tend to collect onthe surface of the manufactured article, hinder the manufacturingprocess of articles made therefrom and may cause the resulting productto have generally undesirable features.

[0005] Because polypropylene is an inexpensive thermoplastic, thereexists a need to improve its workability and to overcome its inherentstiffness and brittleness which limit its commercial application.Therefore, a need exist to safely and economically improve theworkability, flexibility, and/or distensibility of polypropylene.

SUMMARY OF THE INVENTION

[0006] Miscible blends of polypropylene with low molecular weightethylene α-olefin copolymer plasticizers have been discovered. Byblending such miscible, low molecular weight ethylene α-olefin copolymerplasticizers with polypropylene (isotactic polypropylene, syndiotacticpolypropylene and atactic polypropylene), the glass transitiontemperature, storage modulus and viscosity of the blended polypropyleneare lowered. By decreasing the transition temperature, storage modulusand viscosity, the workability, flexibility, and distensibility ofpolypropylene improves. As such, broadened commercial application forthese new polypropylene blends in film, fibers and molded products isapparent. Furthermore, the flexibility of a product design utilizingthese novel blends can be further extended by taking advantage of theenhanced comonomer incorporation and tacticity control possible withmetallocene catalysts, both of which can reduce isotactic polypropylene(“iPP”) crystallinity prior to blending with the low molecular weightethylene α-olefin copolymer plasticizers.

[0007] In one embodiment, a plasticized polypropylene thermoplastic isprovided. The plasticized polypropylene thermoplastic includes from 50to 99.9 weight percent (“wt %”) of a thermoplastic polymer derived frompolypropylene. Optionally, the thermoplastic polymer is copolymerizablewith one or more monomers selected from C₂-C₁₀ α-olefin or diolefin. Thethermoplastic polymer desirably has a melt flow rate (MFR) (ASTM D1238)in the range of from 0.3 to 1000 and a crystallinity, determined bydifferential scanning calorimetry (DSC) at a scan rate of 10° C. perminute, in the range of from 0 to 70% crystallinity. The thermoplasticpolymer is blended with from 0.1 to 50 wt % of at least one ethylenecopolymer. The ethylene copolymer desirably has a weight-averagemolecular weight (M_(w)) (GPC) of from 500 to 10,000, a molecular weightdistribution (MWD) (GPC) of from greater than 1.5 to less than or equalto 3.5, and a comonomer content of from greater than or equal to 20 mol% to less than 70 mol %. The plasticized polypropylene thermoplastic mayinclude from 0 to 20 wt % of the polypropylene thermoplasticcomposition, of a thermoplastic polypropylene modifier compound otherthan the ethylene copolymer described above. Examples of thermoplasticpolypropylene modifier compounds include one or more compositionsselected from the group which includes antioxidants, fillers, pigments,hydrocarbon resins, rosins or rosin esters, waxes, UV stabilizers,additional plasticizers, and tackifiers such as ESCOREZ, a product ofExxon Chemical, which is more fully described in U.S. Pat. No. 5,317,070which is incorporated by reference herein. Additionally, the terminalvinylidene groups present on some of the above thermoplasticpolypropylene modifier compounds may be functionalized, suchfunctionalization being more fully described in U.S. Pat. Nos. 5,763,556and 5,498,809, both of which are incorporated by reference herein.

[0008] The ethylene copolymer may be further described as having a glasstransition temperature (T_(g)) of from greater than or equal to −80° C.to less than or equal to −30° C. In another embodiment, the ethylenecopolymer may be described as having an ethylene crystallinity, asdetermined by differential scanning calorimetry (DSC) at a scan rate of10° C. per minute of less than or equal to 5% crystallinity.

[0009] In another embodiment, the plasticized polypropylenethermoplastic may be further described as having a crystallinity by DSCat a scan rate of 10° C. per minute of less than 60% and wherein the wt% of said ethylene copolymer present in the plasticized polypropylenethermoplastic is less than or equal to y, wherein y is in the range of0.1 to 50, as determined by y in the equation

y=50−0.5x

[0010] where x=the % crystallinity of the thermoplastic polymer.

[0011] In another embodiment, the thermoplastic polymer may be furtherdescribed as having a crystallinity by DSC at a scan rate of 10° C. perminute of greater than or equal to 60% and wherein the wt % of saidethylene copolymer present in the plasticized polypropylenethermoplastic can be as high as 20.

[0012] In another embodiment, the ethylene copolymer component mayinclude, in addition to ethylene, one or more of C₃ to C₂₀ linear orbranched α-olefin or diolefin. Desirably, the ethylene copolymer may beeither an ethylene-propylene, ethylene-butene copolymer, ethylene-hexenecopolymer, ethylene-octene copolymer, ethylene norbornene, ethylenestyrene copolymers, and ethylene-isobutylene copolymers or mixedmonomers including ter-, tetrapolymers, and the like, thereof.

[0013] In another embodiment, a plasticized polypropylene thermoplasticcomposition is provided which includes a blend of a thermoplasticpolymer and the ethylene copolymer. The thermoplastic polymer isdesirably derived from amorphous propylene. Desirably, from 50 to 99.9wt % of the plasticized polypropylene thermoplastic is the thermoplasticpolymer. Optionally the thermoplastic polymer may include one or morecopolymerizable monomers selected from C₂-C₁₀ α-olefin or diolefin. Thethermoplastic polymer has melt flow rate (MFR) (ASTM D1238) in a rangefrom 0.3 to 1000 and a crystallinity, as determined by differentialscanning calorimetry (DSC at a scan rate of 10° C. per minute), in arange from 0 to less than 5%. Desirably, from 0.1 to 50 wt % of theplasticized polypropylene thermoplastic is the ethylene copolymer. Theethylene copolymer has a weight-average molecular weight (M_(w)) (GPC)in a range from 500 to 10,000, a molecular weight distribution (MWD)(GPC) in a range from greater than 1.5 to less than or equal to 3.5, anda comonomer content in a range from greater than or equal to 20 mol % toless than 70 mol %. The plasticized polypropylene thermoplastic may alsoinclude from 0 to 20 wt % thereof of a thermoplastic polypropylenemodifier compound other than the ethylene copolymer. Examples of thisthermoplastic polypropylene modifier include, but are not limited to,antioxidants, fillers, pigments, hydrocarbon resins, rosins or rosinesters, waxes, UV stabilizers, additional plasticizers, singularly or incombination.

[0014] In another embodiment, the plasticized polypropylenethermoplastic may be further described as having a crystallinity by DSCat a scan rate of 10° C. per minute of less than 5% and wherein the wt %of said ethylene copolymer present in the plasticized polypropylenethermoplastic is less than or equal to y, wherein y is in the range of0.1 to 50, as determined by y in the equation

y=50−0.5x

[0015] where x=the % crystallinity of the thermoplastic polymer.

[0016] In another embodiment, a plasticized polypropylene thermoplasticcomposition is provided which includes a blend of a thermoplasticpolymer and the ethylene copolymer wherein the wt % of the ethylenecopolymer in the plasticized polypropylene thermoplastic is less than orequal to y, wherein y is in the range of 0.1 to 50, as determined by yin the equation

y=50−0.5x

[0017] where x=the % crystallinity of said thermoplastic polymer. Thethermoplastic polymer is derived from polypropylene, optionally with oneor more copolymerizable monomer selected from C₂-C₁₀ α-olefin ordiolefin, said thermoplastic polymer having a melt flow rate (MFR) (ASTMD1238) of from 0.3 to 1000. The ethylene copolymer has a weight-averagemolecular weight (M_(w)) (GPC) of from 500 to 10,000, a molecular weightdistribution (MWD) (GPC) of from greater than 1.5 to less than or equalto 3.5, and a comonomer content of from greater than or equal to 20 mol% to less than 70 mol %. In one embodiment, from 50 to 99.9 wt % of theplasticized polypropylene thermoplastic is derived from thethermoplastic polymer and from 0.1 to 50 wt % of the plasticizedpolypropylene thermoplastic is derived from the ethylene copolymer.Desirably, the crystallinity, by differential scanning calorimetry (DSCat a scan rate of 10° C. per minute), of the thermoplastic polymer is ina range of from 0 to 70%.

[0018] In another embodiment, a plasticized polypropylene thermoplasticcomposition formed from a blend of a thermoplastic polymer and anethylene copolymer is provided. The thermoplastic polymer derived frompolypropylene, optionally with one or more copolymerizable monomerselected from C₂-C₁₀ α-olefin or diolefin, said thermoplastic polymerhaving a melt flow rate (MFR) (ASTM D1238) of from 0.3 to 1000. Theethylene copolymer has a weight-average molecular weight (M_(w)) (GPC)of from 500 to 10,000, a molecular weight distribution (MWD) (GPC) offrom greater than 1.5 to less than or equal to 3.5, and a comonomercontent of from greater than or equal to 20 mol % to less than 70 mol %.The wt % of the ethylene copolymer in the thermoplastic composition isless than or equal to y, wherein y is in the range of 0.1 to 50, asdetermined by y in the equation

y=50−0.5x

[0019] where x=the % crystallinity of said thermoplastic polymer.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 illustrates the relationship between the wt % copolymerpresent in the plasticized polypropylene thermoplastic and %crystallinity of the plasticized polypropylene thermoplastic.

[0021]FIG. 2 illustrates dynamic mechanical thermal analysismeasurements of a 50:50 blend of atactic polypropylene and Copolymer 1(an ethylene-butene copolymer, see Table 1).

[0022]FIG. 3 illustrates a tan δ peak for the blend in FIG. 2.

[0023]FIG. 4 illustrates NMR relaxation measurements (T1ρH) for a blendof atactic polypropylene and Copolymer 2 (an ethylene-butene copolymer,see Table 1).

[0024]FIG. 5 illustrates the decreasing effect on Young's modulus ofisotactic polypropylene by blending Copolymers 1-3 therewith (Copolymer3 is an ethylene-butene copolymer, see Table 1).

[0025]FIG. 6 illustrates that energy-to-break for the tensile barsincreases over 50% due to addition of ˜5-15 wt % plasticizer.

[0026]FIG. 7 illustrates a hysterisis series of tensile curves for 60:40wt:wt blend of elastomeric polypropylene and Copolymer 2.

DETAILED DESRIPTION OF THE INVENTION

[0027] This invention relates to (1) plasticized polypropylenethermoplastic compositions, particularly miscible blends ofpolypropylene with low molecular weight ethylene α-olefin copolymerplasticizers; (2) methods for making plasticized polypropylenethermoplastic compositions; and (3) products made from plasticizedpolypropylene thermoplastic compositions. These are described in turnbelow.

[0028] As used herein, “isotactic” is defined as having at least 95%isotactic (meso) pentads according to analysis by ¹³C-NMR. As usedherein, “highly isotactic” is defined as having at least 99% isotacticpentads according to analysis by ¹³C-NMR.

[0029] As used herein, “amorphous” is defined as having less than 5%crystallinity as measured by DSC at a scan rate of 10° C. per minute.

[0030] As used herein, “molecular weight” means weight average molecularweight (M_(w)) and “molecular weight distribution,” (MWD), means M_(w)divided by number average molecular weight (M_(n)) as determined by gelpermeation chromatography (GPC). As used herein, unless otherwisestated, “polymerization” means homopolymerization.

[0031] The plasticized polypropylene thermoplastics described herein area blend of a thermoplastic polymer and an ethylene copolymer. This blendmay also include thermoplastic polypropylene modifiers. These modifiersmay be included in the plasticized polypropylene thermoplasticcompositions. Such modifiers (also known as additives) and their use aregenerally well known in the art.

[0032] Ethylene Copolymer Compositions

[0033] Generally, ethylene copolymers suitable for blending with thethermoplastic polymer, including amorphous and isotactic thermoplasticpolymers, desirably have a weight-average molecular weight (M_(w)) (GPC)of from 500 to 10,000, a molecular weight distribution (MWD) (GPC) offrom greater than 1.5 to less than or equal to 3.5, and a comonomercontent of from greater than or equal to 20 mol % to less than 70 mol %.The wt % of at least one ethylene copolymer present in the plasticizedpolypropylene thermoplastic composition may be from 0.1 to 20 wt %,desirably from 1.0 to 15 wt % and more desirably from 1.0 to 10 wt %.Specific examples of ethylene copolymers include, but are not limited toethylene-propylene, ethylene-butene, ethylene-hexene, andethylene-octene copolymers. Additionally, the ethylene copolymerdesirably has a glass transition temperature (T_(g)) in the range fromgreater than or equal to −80° C. to less than or equal to −30° C., moredesirably from −75° C. to −45° C., most desirably, from −70° C. to −45°C.

[0034] Table 1 illustrates the glass transition temperatures, measuredby DSC at a scan rate of 10° C. per minute, molecular weights andcomonomer concentration of three ethylene/butene copolymers.

[0035] DSC was measured on a TA Instruments model number 2910.Generally, DSC is a measure of the heat flow into or away from a samplepolymer. The sample polymer is placed in one heating chamber, areference material into a separate heating chamber. The sample and areference material are heated at a predetermined rate until heat isemitted or consumed by the sample. The DSC circuitry is programmed tomaintain the same temperature for both the reference and samplechambers. The current necessary to maintain a constant temperaturebetween the sample and reference is recorded. This data provide a directmeasure of the heat of transition of the sample. TABLE 1 Ethylene Mole %M_(w), Copolymer comonomer GPC Tg (Liquid) (butene) (PE std) (DSC, ° C.)Copolymer 1 33.3 7550 −71 (−45)^(a) Copolymer 2 60 8780 −55.3 Copolymer3 66.7 6550 −61.2

[0036] Table 1A illustrates the molecular weights and comonomerconcentration of two ethylene/propylene copolymers. TABLE 1A EthyleneMole % M_(W), Copolymer comonomer GPC Tg (Liquid) (butene) (PE std)(DSC, ° C.) Copolymer 4 38 21,900 Not Measured Copolymer 5 42 3400 −76.0(−52)^(a)

[0037] Copolymers 1-5 may be made in a high pressure reactor. An exampleof such a high pressure reactor would be a staged and baffled reactor (5zones) and have a reactor volume 750 liters, and a 6:1 length/diameterdimension. The residence time in such a reactor may be between 1-2minutes.

[0038] More particularly, the polymerization conditions for copolymers1-5 would include a stirred 750 liter steel autoclave reaction vesselwhich is equipped to perform continuous Ziegler-Natta (Z-N), metalloceneor other single site catalyst polymerization reactions at pressures upto 2500 bar and temperature up to 300° C. The reactor system may beequipped with instrumentation, such as thermocouples and pressuretransducers to continuously monitor temperature and pressure andcontinuous feed systems to continuously supply purified compressedmonomers (e.g., ethylene, butene-1). Additional equipment may alsoinclude a continuous catalyst feed system, a rapid venting and quenchingsystem, and a product separation and collection system. Thepolymerization may be performed without the addition of any externalsolvents. The reactor contents may be stirred continuously duringpolymerization. A typical stirring rate may be about 2,000 rpm. Thetemperature in the reactor may be established and maintained at a targetlevel, such as between 100° C. and 220° C. by pumping the catalystsolution using a continuous high pressure injection pump. See forexample, U.S. Pat. Nos. 5,084,534 and 5,408,017 incorporated byreference for purposes of US patent practice.

[0039] Following polymerization, the polymerized product may beseparated and analyzed, for such purposes as quality control and thelike. The unreacted ingredients may be transported via a recycle loopthrough a cooler and compressor and returned back to the autoclavereactor, along with fresh monomer. As will be recognized by thoseskilled in the art of high pressure Z-N polymerization, the processallows considerable flexibility to modify the molecular weights andcopolymer composition, among other parameters of the polymerizedproducts.

[0040] More specific reactor conditions may include the use ofMe₂Si(H₄-Indenyl)₂ ZrCl₂ as the catalyst and methyl alumoxane (MAO) asthe co-catalyst. The Al/transition metal molar ratio may range from 50:1to 500:1. Reactor pressure may be 20,000 psi or approximately 1350 bar.The reactor exit temperature may be in the range of between 300° F. to370° F., depending upon the target molecular weight. The compositionfeed may be 90 mole % butene-1 and 10 mole % ethylene to achieve atarget 50 wt. % incorporation of butene-1 into the ethylene copolymer.Under these conditions, a production rate of around 2750 lbs/hr. may beachieved.

[0041] The viscosity measurements for copolymers 1, 3-5 are provided inTable 2.

[0042] In keeping with the GPC molecular weight measurements, theviscosity of Copolymer 1 is higher than that of Copolymer 2. Theseviscosities were measured using a Brookfield Viscometer. TABLE 2Viscosity Viscosity Liquid (cP @ ° .C) 50 60 70 90 Copolymer 5 1255 715485 1200 695 445 200 50 70 90 110 Copolymer 1 8810 2850 1230 2910 1250580 Copolymer 3 6010 1880 730 1840 750 360 110 120 140 Copolymer 454,500 39,800 22,800

[0043] The wt % of the ethylene copolymer present in the plasticizedpolypropylene thermoplastic may be described by Equation 1, wherein thewt % of the copolymer is less than or equal to y, wherein y is in therange of 0.1 to 50, as determined by y in Equation 1:

y=50−0.5x

[0044] where x=the % crystallinity of the thermoplastic polymercomposition (described in greater detail below). The relationshipbetween wt % copolymer present in the plasticized polypropylenethermoplastic and % crystallinity is further illustrated in FIG. 1.

[0045] Thermoplastic Polymer Compositions

[0046] Generally, thermoplastic polymers suitable for use in thisinvention may be derived from propylene or may be copolymerized withsmall amounts, generally from 0.1 to 10 mol. % of one or more monomersselected from C₂-C₁₀ α-olefins or diolefins such as for example,ethylene, butene-1, hexene-1 and octene-1. These thermoplastic polymersinclude copolymers and homopolymers and blends, including reactorblends, of amorphous polypropylene, isotactic polypropylene, andmetallocene catalyzed polypropylenes. These thermoplastic polymers mayhave a molecular weight distribution that is in the range of from about2.0 to about 20.0, desirably from about 2.0 to about 12.0, even moredesirably from about 2.0 to about 8.0.

[0047] The thermoplastic polymers compositions of this invention mayhave a weight average molecular weight (M_(w)) that is in the range offrom about 60,000 to about 750,000, and desirably from about 100,000 toabout 500,000, and most desirably from about 150,000 to about 400,000.These thermoplastic polymer compositions may have a melt flow rate (MFR)that is in the range of from about 0.2 dg/min to about 30 dg/min,desirably from about 0.5 dg/min to about 20.0 dg/min, even moredesirably from about 1.0 dg/min to about 10.0 dg/min. The melting pointof the thermoplastic polymer may be less than about 162° C., desirablyless than about 155° C., and most desirably less than about 150° C.Upper limits for melting point depend on the specific application butwould typically not be higher than 170° C. The hexane extractables level(as measured by 21 CFR 177.1520(d)(3)(i)) of the these thermoplasticpolymers may be less than 2.0 wt/o, and desirably less than 1.0 wt %.

[0048] The thermoplastic polymers of this invention can be blended withother polymers, particularly with other polyolefins. Specific examplesof thermoplastic polymers include, but are not limited toethylene-propylene rubber, ethylene-propylene diene rubber, and ethyleneplastomers. Specific examples of commercially available ethyleneplastomers include EXACT™ resins products of Exxon Chemical Company and,AFFINITY™ resins and ENGAGE™ resins, products of Dow Chemical Company.

[0049] Thermoplastic Polypropylene Modifier

[0050] Thermoplastic polypropylene modifiers may be those commonlyemployed with plastics. Examples include one or more of the following:heat stabilizers or antioxidants, neutralizers, slip agents, antiblockagents, pigments, antifogging agents, antistatic agents, clarifiers,nucleating agents, ultraviolet absorbers or light stabilizers, fillers,hydrocarbon resins, rosins or rosin esters, waxes, additionalplasticizers and other additives in conventional amounts. Effectivelevels are known in the art and depend on the details of the basepolymers, the fabrication mode and the end application. In addition,hydrogenated and/or petroleum hydrocarbon resins and other plasticizersmay be used as modifiers.

[0051] The plasticized polypropylene thermoplastic composition mayinclude from 0 to 20 wt % of a thermoplastic polypropylene modifiercompound other than the ethylene copolymer. Desirably, the thermoplasticpolypropylene modifier constitutes greater than 0.001 wt % of theplasticized polypropylene thermoplastic composition.

[0052] Metallocene Catalyzed Thermoplastic Polymers

[0053] The preparation of metallocene catalyzed thermoplastics andparticularly metallocene catalyzed polypropylene involves the use ofmetallocene catalyst systems. Metallocene catalyst systems include ametallocene component and at least one activator. Desirably, thesecatalyst system components are supported on support materials, such asinorganic oxide or polymeric materials.

[0054] Metallocenes

[0055] As used herein “metallocene” and “metallocene component” refergenerally to compounds represented by the formula Cp_(m)MR_(n)X_(q)wherein Cp is a cyclopentadienyl ring which may be substituted, orderivative thereof which may be substituted, M is a Group 4, 5, or 6transition metal, for example titanium, zirconium, hafnium, vanadium,niobium, tantalum, chromium, molybdenum and tungsten, R is a hydrocarbylgroup or hydrocarboxy group having from one to 20 carbon atoms, X is ahalogen, and m=1-3, n=0-3, q=0-3, and the sum of m+n+q is equal to theoxidation state of the transition metal.

[0056] Methods for making and using metallocenes are very well known inthe art. For example, metallocenes are detailed in U.S. Pat. Nos.4,530,914; 4,542,199; 4,769,910; 4,808,561; 4,871,705; 4,933,403;4,937,299; 5,017,714; 5,026,798; 5,057,475; 5,120,867; 5,278,119;5,304,614; 5,324,800; 5,350,723; and 5,391,790 each fully incorporatedherein by reference.

[0057] Methods for preparing metallocenes are fully described in theJournal of Organometallic Chem., volume 288, (1985), pages 63-67, and inEP-A-320762, both of which are herein fully incorporated by reference.

[0058] Desirable metallocene catalyst components are described in detailin U.S. Pat. Nos. 5,145,819; 5,243,001; 5,239,022; 5,329,033; 5,296,434;5,276,208; 5,672,668; 5,304,614; 5,374,752; 5,240,217; and 5,643,847;and EP 549 900 and 576 970 all of which are herein fully incorporated byreference.

[0059] Additionally, metallocenes such as those described in U.S. Pat.No. 5,510,502 (incorporated herein by reference) are suitable for use inthis invention.

[0060] Activators

[0061] Metallocenes are generally used in combination with some form ofactivator. Alkylalumoxanes are desirably used as activators, mostdesirably methylalumoxane (MAO). There are a variety of methods forpreparing alumoxane, non-limiting examples of which are described inU.S. Pat. Nos. 4,665,208, 4,952,540, 5,091,352, 5,206,199, 5,204,419,4,874,734, 4,924,018, 4,908,463, 4,968,827, 5,308,815, 5,329,032,5,248,801, 5,235,081, 5,103,031 and EP-A-0 561 476, EP-B1-0 279 586,EP-A-0 594-218 and WO94/10180, each fully incorporated herein byreference. Activators will also include those comprising or capable offorming non-coordinating anions along with catalytically activemetallocene cations. Compounds or complexes of fluoro aryl-substitutedboron and aluminum are particularly suitable, see, e.g., U.S. Pat. Nos.5,198,401; 5,278,119; and 5,643,847.

[0062] Support Materials

[0063] The catalyst systems used in the process of this invention mayoptionally be supported using a porous particulate material, such as forexample, talc, inorganic oxides, inorganic chlorides and resinousmaterials such as polyolefin or polymeric compounds.

[0064] The most preferred support materials are porous inorganic oxidematerials, which include those from the Periodic Table of Elements ofGroups 2, 3, 4, 5, 13 or 14 metal oxides. Silica, alumina,silica-alumina, and mixtures thereof are particularly preferred. Otherinorganic oxides that may be employed either alone or in combinationwith the silica, alumina or silica-alumina are magnesia, titania,zirconia, and the like.

[0065] The supported catalyst system may be used directly inpolymerization or the catalyst system may be prepolymerized usingmethods well known in the art. For details regarding prepolymerization,see U.S. Pat. Nos. 4,923,833; 4,921,825; and 5,643,847; and EP 279 863and EP 354 893 (each fully incorporated herein by reference).

[0066] Incorporation of the Thermoplastic Polymer with the EthyleneCopolymer

[0067] The plasticized polypropylene thermoplastics may be formed byblending the thermoplastic polymer with the ethylene copolymer. Forsmall quantities sufficient for laboratory examination and analysis, amixer, such as a Brabender mixer, will be sufficient. For larger orcommercial quantities, the liquid ethylene copolymer may be pumpeddirectly into an extruder zone containing the melted thermoplasticpolymer.

[0068] The plasticized polypropylene thermoplastics of this inventionare compositions that can be effectively used in many if not all of theuses known for polypropylene compositions. These uses include, but arenot limited to: hot melt adhesives; pressure sensitive adhesives (as anadhesive component, particularly when the polypropylene has low levelsof crystallinity, e.g., amorphous polypropylene); films (whetherextrusion coatings, cast or blown; such will exhibit improved heatsealing characteristics); sheets (such as by extrusion in single ormultilayer sheets where at least one layer is a plasticizedpolypropylene thermoplastic composition of the invention); any ofmeltblown or spunbond fibers; and, as thermoplastic components inthermoformable thermoplastic olefin (“TPO”) and thermoplastic elastomer(“TPE”) blends where polypropylene has traditionally been demonstratedto be effective. In view of these many uses, with improved lowtemperature properties and increased workability, the plasticizedpolypropylene thermoplastics offer a suitable replacement in selectedapplications for plasticized polyvinyl chloride (PVC).

[0069] The following examples are presented to illustrate the foregoingdiscussion. All parts, proportions and percentages are by weight unlessotherwise indicated. Although the examples may be directed to certainembodiments of the present invention, they are not to be viewed aslimiting the invention in any specific respect.

EXAMPLES Example 1

[0070] The glass transition temperatures measured by dynamic mechanicalthermal analysis (“DMTA”-tan δ peak) for blends of plasticizer liquidsand elastomeric polypropylene (ePP) and amorphous polypropylene (aPP)are listed in Table 3.

[0071] DMTA measurements were determined by placing approximately 0.8grams of the sample in a Rheometrics 25 mm vacuum mold. A plunger isinserted into the mold, using a 1″ spacer to hold the plunger above thevacuum port. This assembly is placed in a Carver press. The samplechamber is evacuated for at least 5 min. at ambient temperature and thenheated to 190° C. and held at that temperature for 10 min. while stillunder vacuum. After this period, the press heater is turned off, thespacer removed, and 5,000 lbs. of pressure applied while a nitrogenpurge is passed through the mold cooling port. Once the sample hascooled to room temperature, the plunger is pushed out of the mold usinga press and the plunger removal tool. Cooling to lower temperature maybe required for samples that cannot easily be removed from mold faces.

[0072] Using a 13 mm wide bar cutter, the sample is cut to size (1 to 2mm×13 mm×20 mm) for DMTA test just prior to use. The Polymer Labs DMTAis calibrated for the A, B and C transducer stiffness settings. L frameand C sample clamps are used for mounting the sample. The testparameters include a single cantilever; peak to peak displacement of 64microns (less for stiffer samples), frequency of 1 or 10 Hz, starttemperature of −140° C., max temperature of 150° C. Temperature isincreased at a rate of 3° C./min.

[0073] Tan δ is the ratio of E″/E′ where E″ is the loss modulus and E′is the elastic modulus or storage modulus.

[0074] These measurements clearly show a pronounced depression in theT_(g) of the polypropylene from ˜273-276° K. Also shown in Table 3 arecalculated T_(g)'s based on equation (2).

1/T _(g) =w ₁ /T _(g1) +w ₂ /T _(g2)

[0075] where w₁ is the weight fraction of component 1, T_(g1) is theglass transition temperature of component 1, w₂ is the weight fractionof component 2, and T_(g2) is the glass transition temperature ofcomponent 2. TABLE 3 Comparison of Measured (DMTA) and Calculated Tg ofPlasticized Amorphous Polypropylenes Blend Tg Measured Tg Calc^(d) a-PP(wt %) Copolymer (wt %) (° K.) (° K.) e-PP^(a) (60) Copolymer 2 (40) 256249 a-PP(50)^(b) Copolymer6^(c) (50) 258 — a-PP(50) Copolymer 2 (50) 245243 a-PP(50) Copolymer 3 (50) 249 238 a-PP(50) Copolymer 1 (50) 242 233# herein.

Example 2

[0076] Density results for two blends of aPP (described in Example 1)with copolymers 1 and 2 are compared with the density of the unblendedaPP are reported in Table 4. Density was measured using a densitygradient column (ASTM D-792). TABLE 4 Density Comparison (23° C.): aPPversus Examples of Plasticized aPP Density, g/cm3 Copolymer CopolymerLiquid, wt % @ 23° C. None  0 0.8525 Copolymer 1 50 0.8591 Copolymer 250 0.8592

[0077] The density measured for the unblended aPP is comparable to thosereported for amorphous polypropylene in the literature. The increaseddensity (0.007 g/cm) of the blends relative to the unblended aPPindicates a substantial reduction in “void volume”. This reduction invoid volume is suggestive of miscibility of the blends.

Example 3

[0078] Dynamic mechanical thermal analysis of the 50:50 blend of aPP(Example 1)+Copolymer 1 was measure, and the results illustrated in FIG.2. The peak in tan δ occurs at 245° K and is illustrated in FIG. 3. Thisvalue is in good agreement with the Tg measured for this blend by DSC ata scan rate of 10° C. per minute (242° K). DMTA of this same aPP withoutplasticizer gives a peak at 276°K.

[0079] DMTA's were measured (not illustrated) for two other blends: ePP(Example 1)+Copolymer 3 and aPP (Example 1)+Copolymer 3. The Tg'smeasured from DMTA and DSC for these three blends are compared in Table5. Agreement between the two methods is good. TABLE 5 Comparison of TgMeasured by DSC and DMTA Blend Thermoplastic Copolymer Tg, ° K. Polymer(wt %) (wt %) DSC DMTA e-PP^(a) (60) Copolymer 2 (40) 256 258 a-PP^(a)(50) Copolymer 2 (50) 245 247 a-PP^(a) (50) Copolymer 1 (50) 242 245

[0080] In all three blend DMTA's, the tan δ peak was substantiallybroader than that for the pure aPP, and markedly skewed to highertemperature as well.

[0081]FIG. 4 illustrates NMR relaxation measurements (T1ρH) for theblend of aPP and Copolymer 2

[0082] Procedure:

[0083] The NMR data were obtained on a Bruker DSX-500 spectrometer usinga variable-temperature 4-mm MAS probe. Radio-frequency power levels were70 kHz for spin-locking and decoupling, corresponding to a H π/2 pulseof 3.5 microseconds. Data were collected at MAS speeds of 4.5-5 kHz.Depending on the temperature, anywhere from 100 to 2,000 scans werecollected per relaxation time increments. T₁ρH measurements were madeusing standard ¹³C cross-polarization observations experiments, in whichthe length of the H spin-lock pulse was incrementally varied prior tocross-polarization. The blend was prepared in toluene solutionscontaining a BHT stabilizer, and dried under nitrogen at ambienttemperature, with further drying at 50° C. in vacuum for 48 hours.

[0084] NMR relaxation measurements also demonstrate miscibility betweenaPP and Copolymer 2 (50:50 wt:wt).

Example 4

[0085] Storage modulus depression data were measured by DMTA asdescribed in Example 1.

[0086] Storage modulus depression can be achieved through manipulationof crystallinity of the polypropylene as well as addition ofplasticizer. The plateau storage modulus of reactor grade aPP(Example 1) at ambient temperature is 0.47 Mpa, or just above 2×10−6dynes/cm (the “Dahlquist Criterion”) for adhesion. Addition of lowmolecular weight ethylene copolymer plasticizer can depress the storagemodulus at least another decade or so, or well below the DahlquistCriterion, thus rendering the polymers exceptionally tacky. A new familyof adhesives could be made based on these blends where first thecrystallinity of the polypropylene is adjusted appropriately with acombination of tacticity defects and comonomer then miscible liquidadded to adjust and optimize the balance of properties. Optionally,miscible tackifiers may also be used. Even with a melting point of 125°C.—corresponding to a crystallinity of just ˜15% and total defects of˜9-10 mole %—one would have a wide Tm-Tg use window on the order of130-140° C.

Example 5

[0087] A summary of ambient temperature properties measured on tensilebars made from a blend of isotactic polypropylene (PD-4062 resin) andCopolymer 2 is provided in Table 6. PD-4062 resin is a polypropylenehomopolymer available from Exxon Chemical. PD-4062 resin has a melt flowrate of 3.9 g/10 min (ASTM D 1238) and a density of 0.90 g/cm (ASTM D792).

[0088] Tensile Measurement Procedure

[0089] Approximately 3 grams of sample is placed in a 2.5″×2.5″×6 milmold template between two pieces of Teflon foil. This assembly is placedbetween the 6″×6″ platens of a Carver Press and heated to 190° C. for 2min. At this point the sample is compressed at 5,000 psi and 190° C. foran additional 2 min. The mold is then removed, placed on coolingplatens, and cooled to room temperature.

[0090] After the sample is removed from the mold, it is inspected forbubbles and imperfections. Tensile specimens are cut from areas havingno visible imperfections using a standard micro “bog bone” cutter (5.5-6mil thickness, 0.08″ in width and 0.197 in length). Five samples werecut from each compression molded plaque. The samples were allowed to ageat least 48 hours before tensile measurements were carried out.

[0091] Each tensile specimen was tested on the Instron 4502 usingserrated grips set at 80 psi. The sample rate was 10 points per secondat a crosshead speed of 2″/min. TABLE 6 Summary of Tensile Bar DataRecorded at Ambient Temperature for Blends of Copolymer 2 with isotacticpolypropylene (PD4062) Wt % Modulus Stress @ % Strain @ Energy-to-BreakCopolymer 2 (kpsi) Yield (kpsi) Max Load (lbs-in) 6 50.3 4.77 845 2.7512.5 40.5 4.1 822 3.18 18 33.2 3.52 690 2.24

Example 6

[0092] A summary of ambient temperature properties measured on tensilebars made from a blend of isotactic polypropylene and Copolymer 3 isprovided in Table 7. TABLE 7 Summary of Tensile Bar Data Recorded atAmbient Temperature for Blends of Copolymer 3 with isotacticpolypropylene (PD4062) Wt % Modulus Stress @ % Energy-to-Break Copolymer3 (kpsi) Yield (kpsi) Strain-to-Brk (lbs-in) 0 55.0 5.68 503 2.29 1041.6 4.32 871 3.62 20 30.0 3.28 848 2.52

Example 7

[0093]FIG. 5 illustrates the roughly linearly decreasing effect onYoung's modulus of isotatic polypropylene by blending Copolymers 2 and 3with isotactic polypropylene (PD4062). In keeping with the data shown inFIG. 4 (DMTA data), the Young's modulus obtained from the tensile barsdecreases—roughly linearly—with increasing plasticizer content. Inaddition, the energy-to-break for the tensile bars increases over 50%due to addition of ˜5-15 wt % plasticizer (maximum around 10 wt %) asillustrated in FIG. 6).

Example 8

[0094] An examination of the large strain behavior/recovery of a verysoft [ePP (described in Example 1)+Copolymer 2] 60:40 wt:wt blend wasundertaken. A hysterisis series of tensile curves (A J Peacockprocedure) is shown in FIG. 7. Elastic recovery of this material is 90%24 hours after 1000% elongation. Elongation to break is ˜1400%.

[0095] Hysterisis Test Procedure

[0096] The hysterisis tests were conducted on the Instron 1123D. Thefilm hysteresis testing procedure used is an Exxon variation of aprocedure described by DuPont in its brochure on its polyether urethaneelastic product, T-722a. In the Exxon variation, 1×6 inch strips aresubjected to successive % strains of 100, 200, 300, 400, 500 and 1,000%(jaw gap separation of 2″ and crosshead speed of 20″/min). The sample isheld for 30 seconds at extension and then retracted and held at 60seconds a relaxation prior to the next extension cycle. FIG. 8illustrates the hysteresis stress/strain curve.

[0097] Tables 8, 9 and 10 provide mechanical properties data for severalpolypropylene liquid blends and comparative data for non-blendedpolypropylene. The mechanical data were generated using various teststhat are listed in the first column of each Table. The procedures forconducting each such test are known and understood by one skilled in theart. TABLE 8 Escorene Escorene RCP PD4062 PD4062 3445 3445 PD9272 10%20% Escorene 10% 20% RCP 10% EB PD4062 EB8D EB8D 3445 EB8D EB8D PD9272P-42-27 Gardner Impact 220. 249.8 222.7 109.3 188.0 20.0 311.3 230.9 RT(B) (DB) (D) (D) (S) (DB) (D) (S) (DB) (D) (D) (in-lbs) (DB) GardnerImpact <8 <8 <8 <8 <8 <8 <8 <8 −29° C. (in-lbs) Notched Impact 0.5780.895 1.159 0.356 0.518 0.388 1.312 1.551 RT (ft-lb/in) Notched Impact0.269 0.178 0.257 0.206 0.219 0.136 0.183 0.279 −18° C. (ft-lb/in)Notched Impact 0.181 0.215 0.189 0.206 0.156 0.144 0.153 0.199 −40° C.(ft-lb/in)

[0098] TABLE 9 PD4062 PD4062 Escorene Escorene RCP 10% 20% Escorene 34453445 10% EB PD4062 EB8D EB8D 3445 10% EB8D 20% EB8D RCP P-42-27 1%Secant Flex 220873 133105 90491 172196 116355 72976 106957 71152 Mod(psi) 1% tangent 227616 140036 96440 175337 124411 78142 110312 74769Flex Mod (psi) Flex Strength 2683 1575 1084 2070 1417 873 1290 859 (psi)Energy at peak 0.229 0.131 0.092 0.173 0.120 0.075 0.108 0.068 (in-lb)

[0099] TABLE 10 PD4062 PD4062 Escorene Escorene RCP 10% 20% Escorene3445 3445 10% EB PD4062 EB8D EB8D 3445 10% EB8D 20% EB8D RCP P-42-27Yield Stress 4922 3885 3045 4591 3569 2592 3316 2510 (psi) Elongation at19.5 29.01 38.23 20.05 28.65 28.63 20.26 29.06 Yield (%) Elongation at349.79 998.02 998.84 357.08 558.36 55.53 998.40 998.21 Break (%) Stressat Break 3164 3187 2998 1617 1490 2355 3067 2586 (psi) Youngs 8559147669 26191 74097 43446 27465 44123 27310 Modulus (psi) Energy @ 13693506 3147 1162 1663 151 2878 2468 Break (in-lb)

[0100] While the present invention has been described and illustrated byreference to particular embodiments, those of ordinary skill in the artwill appreciate that the invention lends itself to many differentvariations not illustrated herein. For these reasons, then, referenceshould be made solely to the appended claims for purpose of determiningthe true scope of the present invention.

[0101] Although the appendant claims have single appendencies inaccordance with U.S. patent practice, each of the features in any of theappendant claims can be combined with each of the features of otherappendant claims of the independent claim.

We claim the following:
 1. A plasticized polypropylene thermoplasticcomposition comprising a blend of: A) from 50 to 99.9 wt % of athermoplastic polymer derived from polypropylene, optionally with one ormore copolymerizable monomer selected from C₂-C₁₀ α-olefin or diolefin,said polymer having a melt flow rate (MFR) (ASTM D1238) of from 0.3 to1000 and a crystallinity by differential scanning calorimetry of from 0to 70%; B) from 0.1 to 50 wt % of at least one ethylene copolymer havinga weight-average molecular weight (M_(w)) (GPC) of from 500 to 10,000, amolecular weight distribution (MWD) (GPC) of from greater than 1.5 toless than or equal to 3.5, and a comonomer content of from greater thanor equal to 20 mol % to less than 70 mol %; and optionally, C) from 0 to20 wt % of a thermoplastic polypropylene modifier compound other thanthat of B).
 2. The polypropylene thermoplastic composition of claim 1wherein said ethylene copolymer has a glass transition temperature(T_(g)) of from greater than or equal to −80° C. to less than or equalto −30° C.
 3. The polypropylene thermoplastic composition of claim 1wherein said ethylene copolymer has less than or equal 5% ethylenecrystallinity by differential scanning calorimetry.
 4. The polypropylenethermoplastic composition of claim 1 wherein said thermoplastic polymerA) has a crystallinity by DSC at a scan rate of 100° C. per minute ofless than 60% and the wt % of said ethylene copolymer is less than orequal to y, wherein y is in the range of 0.1 to 50, as determined by yin the equation y=50−0.5x where x=the % crystallinity of saidthermoplastic polymer A).
 5. The polypropylene thermoplastic compositionof claim 1 wherein said thermoplastic polymer A) has a crystallinity byDSC at a scan rate of 10° C. per minute of greater than or equal to 60%and the wt % of said ethylene copolymer is
 20. 6. The polypropylenethermoplastic composition of claim 2 wherein said ethylene copolymercomprises, in addition to ethylene, one or more of C₃ to C₂₀ linear orbranched α-olefin or diolefin.
 7. The polypropylene thermoplasticcomposition of claim 6 wherein said ethylene copolymer is anethylene-butene copolymer, ethylene-hexene copolymer or ethylene-octenecopolymer.
 8. The polypropylene thermoplastic composition of claim 1wherein said thermoplastic polypropylene modifier compound C)constitutes greater than 0.001 wt % of the total blend and is selectedfrom one or more of the group consisting of antioxidants, fillers,pigments, hydrocarbon resins, rosins or rosin esters, waxes, UVstabilizers, and additional plasticizers.
 9. A plasticized polypropylenethermoplastic composition comprising a blend of: A) from 50 to 99.9 wt %of a thermoplastic polymer derived from amorphous polypropylene,optionally with one or more copolymerizable monomer selected from C₂-C₁₀α-olefin or diolefin, said thermoplastic polymer having a melt flow rate(MFR) (ASTM D1238) of from 0.5 to 1000 and a crystallinity bydifferential scanning calorimetry of from 0 to less than 5%; B) from 0.1to 50 wt % of at least one ethylene copolymer having a weight-averagemolecular weight (M_(w)) (GPC) of from 500 to 10,000, a molecular weightdistribution (MWD) (GPC) of from greater than 1.5 to less than or equalto 3.5, and a comonomer content of from greater than or equal to 20 mol% to less than 70 mol %; and optionally, C) from 0 to 20 wt % of athermoplastic polypropylene modifier compound other than that of B). 10.The polypropylene thermoplastic composition of claim 9 wherein saidethylene copolymer has a glass transition temperature (T_(g)) of fromgreater than or equal to −80° C. to less than or equal to −30° C. 11.The polypropylene thermoplastic composition of claim 9 wherein saidethylene copolymer has less than or equal 5% ethylene crystallinity bydifferential scanning calorimetry.
 12. The polypropylene thermoplasticcomposition of claim 9 wherein said thermoplastic polymer A) has acrystallinity by DSC at a scan rate of 10° C. per minute of less than 5%and the wt % of said ethylene copolymer is less than or equal to y,wherein y is in the range of 0.1 to 50, as determined by y in theequation y=50−0.5x where x=the % crystallinity of said thermoplasticpolymer A).
 13. The polypropylene thermoplastic composition of claim 10wherein said ethylene copolymer comprises, in addition to ethylene, oneor more of C₃ to C₂₀ linear or branched α-olefin or diolefin.
 14. Thepolypropylene thermoplastic composition of claim 13 wherein saidethylene copolymer is an ethylene-butene copolymer, ethylene-hexenecopolymer or ethylene-octene copolymer.
 15. The polypropylenethermoplastic composition of claim 9 wherein said thermoplasticpolypropylene modifier compound C) constitutes greater than 0.001 wt %of the total blend and is selected from one or more of the groupconsisting of antioxidants, fillers, pigments, hydrocarbon resins,rosins or rosin esters, waxes, UV stabilizers, and additionalplasticizers.
 16. A plasticized polypropylene thermoplastic compositioncomprising: a blend of a thermoplastic polymer and an ethylenecopolymer, wherein the thermoplastic polymer derived from polypropylene,optionally with one or more copolymerizable monomer selected from C₂-C₁₀α-olefin or diolefin, said thermoplastic polymer having a melt flow rate(MFR) (ASTM D1238) of from 0.3 to 1000; wherein the ethylene copolymerhas a weight-average molecular weight (M_(w)) (GPC) of from 500 to10,000, a molecular weight distribution (MWD) (GPC) of from greater than1.5 to less than or equal to 3.5, and a comonomer content of fromgreater than or equal to 20 mol % to less than 70 mol %; and wherein thewt % of said ethylene copolymer in the thermoplastic composition is lessthan or equal to y, wherein y is in the range of 0.1 to 50, asdetermined by y in the equation y=50−0.5x where x=the % crystallinity ofsaid thermoplastic polymer.
 17. The plasticized polypropylenethermoplastic composition of claim 16 wherein said ethylene copolymerhas a glass transition temperature (T_(g)) of from greater than or equalto −80° C. to less than or equal to −40° C.
 18. The plasticizedpolypropylene thermoplastic composition of claim 16 wherein saidethylene copolymer has less than or equal 5% ethylene crystallinity bydifferential scanning calorimetry.
 19. The plasticized polypropylenethermoplastic composition of claim 16 wherein said ethylene copolymercomprises, in addition to ethylene, one or more of C₃ to C₂₀ linear orbranched α-olefin or diolefin.
 20. The plasticized polypropylenethermoplastic composition of claim 16 wherein the thermoplastic polymerhas a crystallinity by differential scanning calorimetry of from 0 to70%.